The present invention relates to a method for making a glazing pane having a pattern and to a glazing including the glazing pane.

Patterned glass is well known. It is known to produce sheets of patterned glass by rolling molten glass between a pair of spaced apart rollers, one or both of which has a pattern on the roller surface. The pattern is imparted to the glass surface as the molten glass passes between the rollers. The ribbon of glass so formed is cut into sheets, and the sheets may be cut to size as required.

Such a process requires high energy input to first produce the molten glass. Also, the rollers can be expensive and subject to degradation over time which may affect the pattern that is imparted to the glass. Furthermore the pattern that is applied to the glass cannot be changed once the glass sheets have been made, thereby limiting the designs that may be offered to customers.

It is known from W02015/084902A1 to form patterns in a glass laminate structure by assembling two buffer plates and a glass laminated structure intermediate the two buffer plates. One or both of the two buffer plates includes a pattern formed thereon or therein, or the multi-layer structure includes non- deformable materials forming a pattern. The glass laminate structure is cold formed by heating the assembled structure to a temperature about 5 to 10 degrees above the softening point of the polymer layer for a predetermined period of time at a predetermined pressure . After processing the glass laminate structure can be removed from between the buffer plates wherein the pattern formed in or on the one or both buffers plates or non-deformable materials has been transferred to the glass laminate structure as a function of variances of thicknesses in the glass laminate structure.

The present invention provides an alternative method for making a sheet of patterned glass.

Accordingly the present invention provides from a first aspect a method for making a glazing pane comprising the steps: (i) providing a first sheet of glazing material; (ii) providing an interlayer structure comprising a first sheet of an adhesive interlayer material and a first sheet of plastic material; (iii) positioning the interlayer structure on the first sheet of glazing material such that the first sheet of adhesive interlayer material is between the first sheet of glazing material and the first sheet of plastic material; (iv) providing a pattern plate, the pattern plate having a first major surface and a second opposing major surface, there being a pattern on or in the first major surface of the pattern plate; (v) positioning the pattern plate on the first sheet of plastic material such that the first major surface of the pattern plate faces at least a portion of the first sheet of plastic material; (vi) using suitable lamination conditions to laminate the first sheet of glazing material to the first sheet of plastic material via the first sheet of adhesive interlayer material; and (vii) removing the pattern plate from the sheet of plastic material, wherein during step (vi) the pattern plate is pressed against the first sheet of plastic to form a pattern in the interlayer structure.

The pattern plate may be pressed against the first sheet of plastic during step (vi) for the entire duration of step (vi) or for a shorter duration.

The pattern plate may be provided at any time prior to the pattern plate being positioned on the first sheet of plastic material in step (v).

Preferably step (i) takes place before step (ii).

Preferably the steps take place in the order (i), (ii), (iii), (iv), (v), (vi) and (vii).

Preferably the steps take place in the order (i), (ii), (iv), (iii), (v), (vi), (vii).

The first sheet of glazing material has a first major surface and an opposing major surface.

The first sheet of adhesive interlayer material has a first major surface and an opposing major surface.

The first sheet of plastic material has a first major surface and an opposing second major surface.

The interlayer structure is arranged such that the second major surface of the first sheet of adhesive interlayer material faces the first major surface of the first sheet of plastic.

Preferably the first sheet of glazing material comprises a sheet of glass, in particular a sheet of soda-lime-silica glass or an aluminosilicate glass or a borosilicate glass.

Preferably the first sheet of glazing material comprises a sheet of polycarbonate.

Following step (iii) the first major surface of the first sheet of adhesive interlayer material faces the second major surface of the first sheet of glass and the second major surface of the first sheet of adhesive interlayer material faces the first major surface of the first sheet of plastic material.

Preferably the pattern in the interlayer structure is formed by thickness variations in the interlayer structure.

Preferably the pattern in the interlayer structure is formed by thickness variations in the first sheet of adhesive interlayer material.

Preferably the pattern in the interlayer structure is formed in or on the first sheet of adhesive interlayer material. Preferably the pattern is formed in or on the second major surface of the first sheet of interlayer material.

Preferably the pattern is formed in or on the second major surface of the first sheet of interlayer material and the second major surface of the first sheet of adhesive interlayer material has at least one protrusion thereon and/or at least one indentation therein.

Preferably the pattern in the interlayer structure is formed in or on the first sheet of plastic material.

Preferably the pattern in the interlayer structure is formed in the first sheet of plastic material by causing the first and/or second major surface of the sheet of plastic material to deform.

Preferably the pattern in the interlayer structure is formed in the first sheet of plastic material by causing both the first and second major surfaces of the first sheet of plastic material to deform.

Preferably the pattern in the interlayer structure is in the form of at least one alpha numeric character and/or at least one logo.

Preferably the first sheet of plastic material has a higher melting point than the first sheet of adhesive interlayer material.

Preferably during step (vi) the first sheet of glazing material is laminated to the first sheet of plastic material via the first sheet of adhesive interlayer material at a temperature in the range 5 to 10 °C higher than the softening temperature of the first sheet of adhesive interlayer material.

Preferably during step (vi) the first sheet of glazing material is laminated to the first sheet of plastic material via the first sheet of adhesive interlayer material is at a temperature in the range 60 °C to 150 °C, preferably 90 °C to 140 °C.

Preferably during step (vi) the first sheet of glazing material is laminated to the first sheet of plastic material via the first sheet of adhesive interlayer material at a pressure in the range 5 bar to 20 bar, preferably 5 bar to 16 bar.

Preferably the thickness of the first sheet of glazing material is between 1mm and 25mm, more preferably between 1.4mm and 6.0mm, even more preferably between 1.4mm and 3.0mm.

Preferably the first sheet of adhesive interlayer material comprises polyvinyl butyral (PVB), acoustic modified PVB, a copolymer of ethylene such as ethylene vinyl acetate (EVA), polyurethane (PU) or poly vinyl chloride (PVC).

Preferably the first sheet of adhesive interlayer material has a thickness between 0.3mm and 2.3mm, more preferably between 0.3mm and 1.6mm, even more preferably between 0.3mm and 0.9mm. Preferably the sheet of plastic material has a thickness less than the thickness of the first sheet of adhesive interlayer material.

Preferably the sheet of plastic material has a thickness less than the thickness of the first sheet of glazing material.

Preferably the sheet of plastic material has a thickness greater than about 50 pm.

Preferably the sheet of plastic material has a thickness less than about 1000pm.

Preferably the sheet of plastic material has a thickness between 50pm and 1000pm, more preferably between 50pm and 900pm, or 50pm and 800pm, or 50pm and 700pm, or 50pm and 600pm, or 50pm and 500pm, or 50pm and 400pm, or 50pm and 300pm, or 50pm and 200pm.

Preferably the sheet of plastic material comprises a polyester.

Preferably the sheet of plastic material comprises polyethylene terephthalate (PET).

Preferably the pattern plate comprises at least one of polyethylene terephthalate, polyethylene, polyvinyl chloride, polypropylene, polystyrene, polylactic acid, polycarbonate, acrylic, acrylonitrile butadiene styrene, nylon or polyoxymethylene.

Preferably the pattern plate has a thickness less than 25mm, more preferably less than 20mm, even more preferably between 0.5mm and 10mm, even more preferably between 1mm and 10mm.

Preferably after step (v) and before step (vi) a mould is provided for pressing against the pattern plate during step (vi).

In some embodiments after step (iii) and before step (vi), a second sheet of adhesive interlayer material is provided, and the second sheet of adhesive interlayer material is positioned on the first sheet of plastic material to cover a portion of the sheet of plastic material so that a first portion of the first sheet of plastic material is covered by the second sheet of adhesive interlayer material and a second portion of the first sheet of plastic material is not covered by the second sheet of adhesive interlayer material. In such embodiments, in step (v) the pattern plate faces the second portion of the first sheet of plastic material and is preferably in contact therewith.

Preferably the second sheet of adhesive interlayer material comprises polyvinyl butyral (PVB), acoustic modified PVB, a copolymer of ethylene such as ethylene vinyl acetate (EVA), polyurethane (PU) or poly vinyl chloride (PVC).

Preferably the second sheet of adhesive interlayer material has a thickness between 0.3mm and 2.3mm, more preferably between 0.3mm and 1.6mm, even more preferably between 0.3mm and 0.9mm. Preferably before step (vi) a second sheet of glazing material is provided, and after the second sheet of adhesive interlayer material has been positioned on the first sheet of plastic material, the second sheet of glazing material is positioned on the second sheet of adhesive interlayer material.

Preferably during step (vi) the temperature and pressure is sufficient to join the second sheet of glazing material to the first sheet of plastic material via the second sheet of adhesive interlayer material such that following step (vi), the first sheet of glazing material is joined to the second sheet of glazing material.

Preferably the second sheet of glazing material comprises a sheet of glass, in particular a sheet of soda-lime-silica glass or an aluminosilicate glass or a borosilicate glass.

Preferably the second sheet of glass has been chemically strengthened.

Preferably the second sheet of glass is chemically strengthened to have surface compressive stress greater than 400MPa, more preferably between 400MPa and 900MPa, even more preferably between 400MPa and 700MPa, even more preferably between 450MPa and 675MPa.

Preferably the second sheet of glass is chemically strengthened to have a depth of layer (DOL) between 10 pm and 60pm, more preferably between 25pm and 45pm, even more preferably between 30pm and 40pm.

Preferably the second sheet of glazing material comprises a sheet of polycarbonate.

Preferably the thickness of the second sheet of glazing material is between 0.3mm and 1.0mm.

Preferably after the second sheet of glazing material has been positioned on the second sheet of adhesive interlayer material a mould is provided for pressing against the second sheet of glazing material during step (vi). The mould may also press against the pattern plate during step (vi).

Preferably the mould is used to cold form the second sheet of glazing material during step (vi).

Preferably the mould has a shape substantially the same as a shape of the first sheet of glass.

In embodiments when a second sheet of adhesive interlayer is positioned on the sheet of plastic material followed by positioning a second sheet of glazing material on the second sheet of adhesive interlayer material, it is preferred that steps (iv) and (v) take place after the second sheet of glazing material has been so positioned.

In embodiments when a second sheet of adhesive interlayer is positioned on the sheet of plastic material followed by positioning a second sheet of glazing material on the second sheet of adhesive interlayer material, it is preferred that the pattern plate has a thickness the same or greater than the combined thickness of the second sheet of adhesive interlayer material and the second sheet of glazing material.

In other embodiments the pattern in the interlayer structure is formed in the sheet of plastic material by causing both the first and second major surfaces of the sheet of plastic material to deform and the first and second major surfaces of the sheet of plastic material each have a first deformation, and the first deformation on the first major surface of the sheet of plastic is aligned with the first deformation on the second major surface of the sheet of plastic.

Preferably the first deformation on the first major surface of the first sheet of plastic is a protrusion and the first deformation on the second major surface of the first sheet of plastic is an indentation.

Preferably the first deformation on the first major surface of the sheet of plastic is an indentation and the first deformation on the second major surface of the sheet of plastic is a protrusion

In embodiments when a mould is used, preferably the mould has a shape substantially the same as a shape of the first sheet of glass.

In some embodiments the sheet of plastic material is a carrier ply for a coating.

In such embodiments, preferably the plastic material comprises polyethylene terephthalate (PET).

Preferably the sheet of plastic material has a coating on at least a portion of a major surface thereof. Preferably the coating on the major surface of the sheet of plastic material covers the entire major surface of the sheet of plastic material.

Preferably the coating on the sheet of plastic material is a solar control coating, more preferably a solar control coating comprising one or more layer of silver.

Preferably the coating on the sheet of plastic material faces the first sheet of adhesive interlayer material.

The present invention also provides from a second aspect a glazing pane made by a method according to the first aspect of the present invention.

Preferably the glazing pane is a pane in an insulated glazing unit, the glazing pane being spaced apart from another pane of glazing material by a perimeter seal.

The space bounded by the glazing pane and the another glazing pane and the perimeter seal defines a cavity. Preferably the sheet of plastic material faces into the cavity. Other embodiments of the first and/or second aspects present invention have other preferable features.

Preferably the first sheet of glazing material is a coated sheet, there being a coating on the first and/or second major surface of the first sheet of glazing material. The coating on the first and/or second maj or surface of the first sheet of glazing material may be a low emissivity coating or a solar control coating .

Such coatings are known in the art and may comprise one or more layer of silver.

Preferably the first sheet of glazing material is a sheet of float glass.

Preferably the first sheet of glazing material is a sheet of soda-lime-silicate glass.

Preferably the first sheet of glazing material has soda-lime-silicate glass composition comprising (by weight), Si0 ₂ 69- 74 %; A1 ₂ 0 ₃ 0 - 3 %; Na ₂ 0 10 - 16 %; K ₂ 0 0 - 5 %; MgO 0 - 6 %; CaO 5 - 14 %; S03 0 - 2 %.

Preferably the first sheet of glazing material has a soda-lime-silicate glass composition comprising (by weight), Si0 ₂ 69 - 74 %; A1 ₂ 0 ₃ 0 - 3 %; Na ₂ 0 10 - 16 %; K ₂ 0 0 - 5 %; MgO 0 - 6 %; CaO 5 - 14 %; S03 0 - 2 % and Fe ₂ 0 ₃ 0.005 - 2 %. Preferably the first sheet of glazing material is a sheet of thermally toughened glass or thermally semi-toughened glass.

Embodiments having a second sheet of glazing material have preferable features.

Preferably the second sheet of glazing material is an alkali aluminosilicate glass composition.

Preferably the second sheet of glazing material includes at least about 6wt% aluminium oxide. Preferably the second sheet of glass has a composition comprising 66-72 mol. % Si0 ₂ , 1-4 mol. %

A1 ₂ 0 ₃ , 8-15 mol. % MgO, 1-8 mol. % CaO, 12-16 mol.% Na ₂ 0, preferably wherein MgO + CaO is between 12 and 17 mol. % and CaO/(MgO + CaO) is in the range 0.1 and 0.4.

Preferably the second sheet of glass has a composition comprising (by weight) 58% to 70% Si0 ₂ , 5% to 15% A1 ₂ 0 ₃ , 12% to 18% Na ₂ 0, 0.1% to 5% K ₂ 0, 4% to 10% MgO and 0% to 1% CaO with the provisos that the sum of the A1 ₂ 0 ₃ and MgO exceeds 13%, that the sum of the amounts of A1 ₂ 0 ₃ plus MgO divided by the amount of K ₂ 0 exceeds 3 and that the sum of the Na ₂ 0 plus K ₂ 0 plus MgO exceeds 22%.

Preferably the second sheet of glass is chemically strengthened to have a surface compressive stress greater than 400MPa, preferably between 400MPa and 900MPa, more preferably between 400MPa and 700MPa, even more preferably between 450MPa and 675MPa. Preferably the second sheet of glass is chemically strengthened to have a surface compressive stress of around 900MPa or less.

Preferably the second sheet of glass is chemically strengthened to have a depth of layer (DOL) between 10 pm and 60pm, more preferably between 25pm and 45pm, even more preferably between 30pm and 40pm.

The present invention will now be described with reference to the following figures (not to scale) in which:

Figure 1 is a schematic cross-sectional view of an unlaminated stack of components used to make a laminated glazing in accordance with the present invention;

Figure 2 is a schematic cross-sectional view of a laminated glazing pane and pattern plate being removed;

Figures 3 and 4 are magnified views of portions of the pattern plate and interlayer structure before and after lamination;

Figure 5 is a schematic isometric representation of another glazing pane made in accordance with the present invention;

Figure 6 is a schematic plan view of the glazing pane shown in figure 5;

Figure 7 is a schematic plan view of another glazing pane having a pattern in a lower region;

Figure 8 is a schematic isometric representation of another glazing pane made in accordance with the present invention;

Figure 9 is a schematic plan view of the glazing pane shown in figure 8;

Figure 10 is a schematic plan view of a vehicle side window made in accordance with the present invention;

Figure 11 is a schematic cross-sectional representation of the vehicle side window shown in figure 10;

Figure 12 is an exploded schematic of the laminated glazing shown in figure 11, but horizontally arranged;

Figure 13 is a schematic isometric representation of the unlaminated components used to make the laminated glazing shown in figure 11 ;

Figure 14 is a flowchart to illustrate the steps used in carrying out a method in accordance with the present invention; and

Figure 15 is a schematic cross-sectional representation of an insulated glazing unit that includes a glazing pane made in accordance with the present invention. Figure 1 shows a schematic cross-sectional view of an unlaminated stack of components 2 used to make a glazing pane in accordance with the present invention. The components in the unlaminated stack 2 are shown spaced apart to help with the description thereof.

The unlaminated stack 2 comprises a first sheet of glass 4 having a thickness of 6mm, a first sheet of PVB 6 having a thickness of 0.76mm and a sheet of PET 8 having a thickness of lOOpm. In the unlaminated stack 2 the edges of the first sheet of glass 4, the first sheet of PVB 6 and the sheet of PET 8 are all aligned i.e. the components in the unlaminated stack 2 are congruently stacked. In this example the sheet of PET is uncoated but in an alternative example the sheet of PET has a solar control coating on a major surface thereof, in particular on the major surface of the sheet of PET facing the first sheet of PVB 6.

A pattern plate 10 having a first major surface 12 and an opposing second major 14 is positioned on the sheet of PET 8 by moving in the direction of arrow 16. The pattern plate 10 positioned on the sheet of PET 8 is shown in phantom and designated by reference numeral 10’.

There is a pattern on and in the first major surface 12 of the pattern plate 10. The pattern plate 10 is made of polycarbonate so does not adhere to PET at the temperatures and pressures used to laminate the sheet of PET to the first sheet of glass 4. The pattern plate 10 is about 4mm thick and parts of the pattern on the first major surface 12 are proud thereof by about 0.5mm and parts of the pattern in first major surface are about 0.5mm deep. The pattern extends over the entire major surface 12, but may extend over only a selected portion thereof.

The unlaminated stack of components with the pattern plate 10 pressed against the sheet of PET 8 undergoes a lamination process at a suitable temperature and pressure to join the sheet of PET 8 to the first sheet of glass 4 via the first sheet of PVB 6. For example, the lamination process may be carried out in an autoclave at a temperature in the range 90 °C to 140 °C and a pressure in the range 8 bar to 16 bar.

Following lamination, a glazing pane 1 is produced as shown in figure 2 and the pattern plate 10 is removed from the surface of the PET 8 (i.e. in the direction of arrow 18) because the pattern plate 10 does not adhere to the sheet of PET 8 during the lamination process.

The interlayer structure of sheet of PET 8 and first sheet of PVB 6 has a pattern formed therein due to the pattern plate 10 pressing against the sheet of PET 8 during the lamination process.

Figure 3 is a zoomed in view of a portion of figure 1 to illustrate the pattern associated with the first major surface 12 of the pattern plate 10.

As described above, the pattern plate 10 is positioned on the exposed surface 8a of the sheet of PET 8 by moving the pattern plate 10 in the direction of arrow 16. The pattern plate 10 has a first major surface 12 for contacting the exposed surface 8a, and an opposing second major surface 14. In this example the pattern plate 10 has two protrusions 10a, 10b on the first major surface 12 and an indention 10c in the first major surface 12. The two protrusion 10a, 10b and the indentation form the pattern associated with the pattern plate 10.

The protrusion 10a is triangular in cross section whereas the protrusion 10b is semi-circular in cross section. The indentation 10c is also triangular in cross section. Other shape of protrusion and/or indentation may be provided.

The protrusions 10a, 10b and/or the indentation 10c may extend from one side of the pattern plate to the other, or may by formed in localised regions of the first major surface 12.

Following lamination to produce the glazing pane 1, the pattern plate 10 is removed from the sheet of PET 8 and this is shown in figure 4.

The pattern plate 10 is moved in the direction of arrow 18 following lamination of the unlaminated stack 2. The pattern on or in the first major surface 12 of the pattern plate is transferred to the interlayer structure consisting of the first sheet of PVB 6 and the sheet of PET 8, thereby forming a pattern in the interlayer structure.

The protrusion 10a causes an indentation 10a’ in the surface 8a of the sheet of PET 8. The protrusion 10b also causes an indentation 10b’ in the surface 8a. The indentation 10a’ is essentially an imprint of the protrusion 10a. Likewise, the indentation 10b’ is essentially an imprint of the protrusion 10b.

The protrusion 10a also causes an indentation 10a” to form in the surface of the first sheet of PVB 6 not in contact with the sheet of glass 4. Likewise, the protrusion 10b also causes an indentation 10b” to form in the surface of the first sheet of PVB 6 not in contact with the sheet of glass 4. The indentation 10a’ and 10a” may have different shapes in cross section, depending upon the amount of pressure applied to the spacer during lamination, and also the temperature of the lamination process. The indentations 10a’ and 10a” each cause a local variation in the thickness of the interlayer structure. Similarly, the indentations 10b’ and 10b” each cause a local variation in the thickness of the interlayer structure.

The indentation 10c causes a protrusion 10c’ to form on the surface 8a. The indentation 10c also causes a protrusion to form on the surface of the first sheet of PVB 6 not in contact with the sheet of glass 4. The protrusions 10c’ and 10c” cause a local variation in the thickness of the interlayer structure.

The indentations 10a’, 10b’ and the protrusion 10c’ are a form of wrinkling of the surface 8a of the sheet of PET 8 when pressure is applied to the pattern plate 10 (with the pattern plate 10 in contact with the surface 8a) during lamination. Figure 5 shows a schematic isometric representation of another glazing pane made in accordance with the present invention. The glazing pane 20 is similar in construction to the glazing pane 1 shown in figure 2 but the glazing pane 20 has a pattern 30 in a first portion 32 thereof, a second portion 34 of the glazing pane 20 not having a pattern. Such a glazing pane 20 is made in accordance with the present invention by using a pattern plate that extends over only the first portion 32 during lamination.

The glazing pane 20 comprises a sheet of glass 24 joined to a sheet of PET 28 by means of a sheet of PVB 26. The sheet of PVB 26 as a thickness of 0.76mm and the sheet of PET 28 has a thickness of about 50 pm, although the thickness of the sheet of PET 28 may be in the range 50 pm - 500 pm. The sheet of glass 24 has a thickness of 4.85mm but may be in the range of about 0.5mm to 25mm. Instead of PVB, EVA may be used.

The sheet of PVB 26 is in direct contact with and coextensive with the sheet of glass 24. The sheet of PET 28 is in contact with and coextensive with the sheet of PVB 26.

The sheet of glass 24 has four sides defining a periphery of the sheet of glass.

In accordance with the present invention the glazing pane 20 has a pattern in the first portion 32. In this example the pattern 30 consists of a plurality of straight lines (only 30a and 30b are labelled) and the pattern was formed during the lamination process due to the incorporation of a pattern plate having the same pattern thereon.

A view of the glazing pane 20 in the direction of arrow 31 is shown in figure 6. The arrow 31 is normal to the surface of the PET in the first portion 32.

The pattern 30 may be on or in the sheet of PET 28 in the first portion 32. In addition, or instead of, the pattern 30 may be in or on the sheet of 26 in the first portion 32. There is no pattern in the second portion 34 and the optical quality in the second portion 34 is greater than the optical quality in the first portion.

Figure 7 shows a plan view of another glazing pane 40 which has the same construction as the glazing pane 20 described with reference to figure 5, except during the lamination process a different pattern plate was used to produce a different pattern in the first portion 32.

In this example a pattern 42 was produced in the first portion 32 that was in the form of a logo, the logo having a graphical portion 42a being a solid ring shape, and a text portion 42b consisting of the letters “abc”.

Figure 8 is a schematic isometric representation of another glazing pane 50 that has been made in accordance with the present invention. The glazing pane 50 comprises a first sheet of glass 54 joined to a second sheet of glass 64 by means of an interlayer structure consisting of a first sheet of PVB 56, a second sheet of PVB 66 with a sheet of PET 58 therebetween.

The first sheet of glass 54 has a thickness of 4mm and is a sheet of toughened soda-lime-silica glass. The first sheet of PVB 56 has a thickness ofO.38mm and the second sheet of PVB has a thickness of 0.5mm. The sheet of PET has a thickness of 50 pm.

The first sheet of PVB 56 is in contact with and coextensive with the first sheet of glass 54. The sheet of PET 58 is in contact with and coextensive with the first sheet of PVB 56.

Each of the first and second sheets of glass 54, 64 has four sides defining a respective periphery of the glass sheet. Each of the first and second sheets of glass 54, 64 has a respective first major surface and opposing second major surface. The first and second major surfaces of the first sheet of glass 54 are greater in area than the first and second major surfaces of the second sheet of glass 64.

The periphery of the second sheet of glass 64 is aligned with the periphery of the first sheet of glass 54 along three sides, and because the second sheet of glass 64 has smaller major surfaces than the first sheet of glass 54, the glazing pane 50 is essential divided into a first portion 72 and a second portion 74.

As can be seen from figure 8, a portion of the sheet of PET 58 is covered by the second sheet of PVB 66 and the second sheet of glass 64 (i.e. in the second portion 74), and the portion of the sheet of PET 58 not covered by the second sheet of PVB 66 and the second sheet of glass 64 has an exposed surface.

In accordance with the present invention the first portion 72 has a pattern 70. In this example the pattern 70 consists of a plurality of straight lines (only 70a and 70b are labelled) and the pattern was formed during the lamination process due to the incorporation of a pattern plate having the same pattern thereon being positioned on the exposed portion of the sheet of PET 58 and being pressed against the exposed portion of the sheet of PET 58 during lamination.

A plan view of the glazing in the direction of arrow 71 is shown in figure 9. The arrow 71 is normal to the surface of the exposed PET in the first portion 72.

Figure 10 shows a plan view of a vehicle side window 80 made using a method in accordance with the present invention. In plan view, the vehicle side window 80 has an upper region 83, a lower region 85 and a connection region 87.

The upper region 83 is defined in relation to a line x-x’, and the line x-x’ is defined by the styling of the vehicle into which the vehicle side window is installed. In this example the connection region 87 comprises a first trapezoidal portion 87a and a second trapezoidal portion 7b. Each trapezoidal portion 87a, 87b has a respective hole 87c, 87d at the narrow end thereof. The holes 87c, 87d are used to connect a winder mechanism (not shown) to the vehicle side window 80 to move the vehicle side window vertically, i.e. in the direction of arrow 88.

The vehicle side window 80 has a major surface 81 configured for use as an outer surface. The major surface 81 has a central region 82, the central region being inboard of the periphery of the vehicle side window 80.

Figure 11 shows a schematic cross-sectional representation of the laminated glazing 80 taken along the line y-y’ in figure 10.

The line x’-x” forms a horizontal plane with the line x-x\ The regions 83, 85 and 87 are defined in the same way as with reference to figure 10.

As can be seen from figure 11, the laminated glazing 80 has a first sheet of glass 84 joined to a second sheet of glass 94 by means of an interlayer structure 90. The first sheet of glass 84 has a first major surface 84a and a second opposing major surface (not labelled in this figure). The second sheet of glass 94 has a first major surface (not labelled in this figure) and a second opposing major surface 94b.

The interlayer structure 90 consists of a first sheet of PVB 86 having a thickness of 0.76mm, a second sheet of PVB 92 having a thickness of 0.76mm and a sheet of PET 88 having a thickness of 50 pm. Each of the first and second sheets of PVB 86, 92 have a respective first major surface and opposing second major surface. The sheet of PET 88 also has a first major surface and a second opposing major surface (labelled as 88b).

The sheet of PET 88 is able to function as a support sheet and is between the first and second sheets of PVB 86, 92. In the event of breakage of the first sheet of glass 84, the first and second sheets of PVB 86, 92 remained adhered to the sheet of PET 88 so that the second sheet of glass 94 does not become detached from the laminated glazing 80.

The first sheet of PVB 86 is coextensive with the first sheet of glass 84. The first sheet of PVB 86 may be slightly inboard the edge of the first sheet of glass 84, especially in the upper region 83.

The sheet of PET 88 is coextensive with the first sheet of PVB 86 and may be part of a composite structure, for example the sheet of PVB 86 may be joined to the sheet of PET 88 prior to laminating the first sheet of glass 84 to the second sheet of glass 94 by means of the interlayer structure 90.

The exposed major surface 88b of the sheet of PET 88 may have a coating thereon, for example an anti-abrasion hard coat or a solar control coating. Prior to being incorporated into the laminated glazing 80, such a coating may extend over the entire exposed major surface of the sheet of PET 88. In such an example, the second sheet of PVB 92 would be in direct contact with the coating instead of being in direct contact with the sheet of PET 88. In such an example the second sheet of PVB 92 is still on the sheet of PET 88.

The second sheet of PVB 92 is coextensive with the second sheet of glass 94. However the second sheet of PVB 92 and the second sheet of glass 94 are not coextensive with the first sheet of glass 84.

The first sheet of glass 84 is a sheet of soda-lime-silicate glass having a composition such as clear float glass, typically with the addition of iron oxide as a tinting agent to provide the laminated glazing with some form of solar control. The first sheet of glass may have a different composition, such as a borosilicate glass composition or an aluminosilicate glass composition.

In this example the first sheet of glass 84 has a thickness of 2.9 mm and has been thermally toughened using a conventional high pressure cooling air technique such that the compressive stress in at least the central region 82 of the first sheet of glass 84 is around 90 MPa.

The second sheet of glass 94 has a thickness of 0.6 mm but may have a thickness in the range of 0.3 mm to 0.8 mm, for example 0.4 mm to 0.8 mm. The second sheet of glass 94 may have a thickness of 0.55mm or 0.7mm.

The second sheet of glass 94 has been chemically strengthened using a conventional molten salt ion exchange process to exchange sodium ions in the surface of the second sheet of glass with potassium ions from a suitable molten salt. The chemical strengthening process is controlled to provide the second sheet of glass with a depth of layer (DOL) of 35pm and a surface compressive stress greater than 400MPa, typically between 450MPa and 700MPa. The surface compressive stress may be as high as 900MPa. The DOL may be between 30pm and 40pm.

It is known in the art that surface compressive stress measurements of non-chemically strengthened glass (i.e. thermally toughened or strengthened soda-lime-silicate glass) may be made using a Strainoptics Laser GASP-CS (http://www.strainoptics.com/files/Laser%20GASP-CS%20Quick- Start%20(English).pdf). Such equipment is available from Strainoptics, Inc., 108 W. Montgomery Avenue, North Wales, PA 19454 USA. For high levels of surface compressive stress, as typically found in chemically strengthened glass and fully thermally toughened soda-lime-silicate glass, it is known in the art that a differential stress refractometer (DSR) may be used to measure surface compressive stress. Such equipment is available from Gaertner Scientific Corporation, 3650 Jarvis Avenue, Skokie, Illinois 60076 USA.

A specific composition for the second sheet of glass 94 is 68 mol% S1O2, 2.5 mol% AI2O3, 11 mol% MgO, 3.7 mol% CaO, 14.2 mol% Na ₂ 0, 0.6 mol% K2O. For this composition MgO + CaO is 14.7 mol% and Na ₂ 0 + K2O is 14.8 mol%. This is composition number 13 in table 2 on page 20 of W02014/148020A1 as published. The iron oxide (Fe ₂ C> ₃ ) content of the second sheet of glass may be low, being less than 0.1 percent by weight i.e. about 0.012 percent by weight.

As shown in figure 11, hole 87d passes through the first sheet of glass 84, the first sheet of PVB 86 and the sheet of PET 88.

As figure 11 shows, part of the interlayer structure 90 extends below the line x’-x”, and consequently below the line x-x’ in figure 10.

As discussed above, the first sheet of PVB 86 is coextensive with both the sheet of PET 88 and the first sheet of glass 84. As such, the first sheet of PVB 86 and the sheet of PET 88 extend below the line x’- x” (and x’-x’ in figure 10) to cover the lower region 85, which includes the connection region 87. The region of the hole 87d is also surrounded by PVB (from the first sheet of PVB 86) and PET (from the sheet of PET 88).

The laminated glazing 80 was made in accordance with the present invention. During a suitable lamination step a pattern plate 100 (shown displaced in figure 11) was pressed against the exposed PET in the lower region 85 i.e. against the exposed portion of the second major surface 88b of the sheet of PET 88. The first major surface 100a of the pattern plate 100 has a pattern therein and during the suitable lamination process the first major surface 100a is pressed against the exposed portion of the second major surface 88b of the sheet of PET 88 to transfer the pattern in the first major surface 100a to the portion of the interlayer structure 90 in the lower region 85.

It has been found that by having a pattern plate with a thickness substantially the same as the combined thickness of the second sheet of PVB 92 and the second sheet of glass 94 that during lamination the optical quality of the laminated glazing in the upper region 83 may be improved because the pattern plate 100 allows more uniform pressure to be applied to the unlaminated stack.

A mould may be used during the suitable lamination step to press against the pattern plate 100 and the second sheet of glass 94. The mould may be used to cold form the second sheet of glass 94 to the shape of the first sheet of glass 84 during the suitable lamination step.

Figure 12 is an exploded schematic of the laminated glazing 80 shown in figure 11, but in a horizontal arrangement. Figure 12 is illustrative of the individual components used to make up the laminated glazing prior to being laminated together in accordance with the present invention.

As more easily seen in figure 12, the first sheet of glass 84 has a first major surface 84a and a second opposing major surface 84b. The second sheet of glass 94 has a first major surface 94a and a second opposing major surface 94b. The second major surface 84b faces the first major surface 94a. The first sheet of PVB 86 has a first major surface 86a and a second opposing major surface 86b. The sheet of PET 88 has a first major surface 88a and a second opposing major surface 88b. The second sheet of PVB 92 has a first major surface 92a and a second opposing major surface 92b.

There may be a coating on the first and/or second major surface 88a, 88b of the sheet of PET 88, in particular a solar control coating.

Each of the first sheet of glass 84, the first sheet of PVB 86 and the sheet of PET 88 have a respective hole 84d, 86d, 88d therein, and the holes 84d, 86d, 88d align in the laminated glazing 80 to form hole 87d.

Figure 13 is a schematic isometric representation of the unlaminated components used to make the laminated glazing 80.

With reference to figures 12 and 13, to make the laminated glazing 80, the first sheet of glass 84 is initially placed onto a suitable support such that the second major surface 84b faces upwards. With reference to figure 13, in an embodiment the first sheet of glass 84 is initially positioned on a sheet of glass 111 having the same shape as the first sheet of glass 84, or a shape such that the first sheet of glass 84 nests on the sheet of glass 111. The sheet of glass 111 functions as a mould and a support to support the first sheet of glass 84 during lamination and is not part of the resultant laminated glazing 80.

Next the first sheet of PVB 86 is placed onto the first sheet of glass 84 such that the second major surface 86b faces upwards and the hole 86d is aligned with the hole 84d in the first sheet of glass. A hole 86c in the first sheet of PVB aligns with a hole 84c in the first sheet of glass. The periphery of the first sheet of PVB 86 is aligned with the periphery of the first sheet of glass 84 i.e. the first sheet of PVB 86 is congruently stacked on the first sheet of glass 84. Alternatively, and with reference to figure 13, an over sized sheet of PVB 184 may be used instead of a pre-cut sheet of PVB 84. The over-sized sheet of PVB 184 may be positioned on the first sheet of glass 84 and cut to size by trimming off the excess PVB 184’ using the periphery of the first sheet of glass 84 as a template.

Next a sheet of PET 88 is placed on the first sheet of PVB 86 such that the hole 88d in the sheet of PET 88 is aligned with the hole 86d in the first sheet of PVB 86b and the second major surface 88b faces upwards. A hole 88c in the sheet of PET 88 aligns with hole 86c in the first sheet of PVB. The periphery of the sheet of PET 88 is aligned with the periphery of the first sheet of PVB 86 i.e. the first sheet of glass 84, the first sheet of PVB 86 and the sheet of PET 88 are congruently stacked. Alternatively, and again with reference to figure 13, an over-sized sheet of PET 188 may be used instead of a pre-cut sheet of PET 88. The over-sized sheet of PET 188 is positioned on the first sheet of PVB 86 and cut to size by trimming off the excess PET 188’ using the periphery of the first sheet of glass 84 with first sheet of PVB 86 thereon as a template. The holes 84d, 86d and 88d align to create hole 87d, see figure 10.

Next the second sheet of PVB 92 is placed on the second major surface 88b of the sheet of PET 88 such that the second major surface 92b faces upwards. Three sides of the periphery of the second sheet of PVB 92 are aligned with the portions of the periphery of the sheet of PET 88.

Finally the second sheet of glass 94 is positioned on the second sheet of PVB 92. The periphery of the second sheet of glass 94 is aligned with the periphery of the second sheet of PVB 92 i.e. the second sheet of glass 94 is congruently stacked with the second sheet of PVB 92. .

In accordance with the present invention, a pattern plate 100 is positioned on the exposed PET (the portion of the sheet of PET 88 not covered by the second sheet of PVB 92 and the second sheet of glass 94). As shown in figures 12 and 13, the pattern plate 100 is moved in the direction of arrow 101 onto the exposed portion of the second major surface 88b of the sheet of PET 88.

The pattern plate 100 has a first major surface 100a and a second opposing major surface 100b. The shape of the major surface 100a is configured to nest with the sheet of PET 88 on the first sheet of PVB 86 and the first sheet of glass 84 in the lower region 85. The first sheet of PVB 86 and the sheet of PET 88 each have major surfaces that are parallel to each other. Accordingly, the shape of the major surface 100a is configured to nest with the first sheet of glass 84 in the lower region 85.

The thickness of the pattern plate 100 is substantially the same as the combined thickness of the second sheet of glass 94 and the second sheet of PVB 92. For example, if the second sheet of PVB 92 has a thickness of 0.38mm and the second sheet of glass 94 has a thickness of 0.7mm, the pattern plate preferably has a thickness of 1 08mm. It has been found that if the second major surface 100b of the pattern plate 100 is aligned with the second major surface 94b of the second sheet of glass 94 when the pattern plate 100 is positioned on the exposed portion of the sheet of PET 88, following lamination the optical quality in the upper region is improved compared to not using the pattern plate 100.

In this example, the pattern plate 100 has a pattern in the first major surface 100a that is transferred to the lower region as previously described. The pattern in the first major surface 100a may be engraved into the surface at a depth that is small in comparison to the thickness of the pattern plate.

The pattern plate 100 is made of a material that does not adhere to the surface of the sheet of PET 88. In this example, polycarbonate was used.

The periphery of the pattern plate 100 may be aligned with the periphery of the sheet of PET 88 in the lower region 85. In an alternative, and with reference to figure 13, the pattern plate 100 may be replaced with a pattern plate 200. The pattern plate 200 has a similar periphery to the pattern plate 100 but is not aligned with the space between the two trapezoidal portions 87a and 87b. In another alternative, a pattern plate 300 may be used which has a rectangular outline periphery.

With the pattern plate 100 on the exposed portion of the second major surface 88b of the sheet of PET 88 the unlaminated stack may be laminated together by laminating at suitably high temperature and pressure. During lamination the pattern plate 100 is pressed against the sheet of PET 88 to transfer the pattern to the interlayer structure in the lower region 85.

In an alternative embodiment, a mould 110 is used. Prior to lamination, the mould 110 is positioned on the second sheet of glass 94 and the pattern plate 100 by moving the mould 110 in the direction of arrow 112. In this example the mould is a glass sheet having smooth major surfaces. Other material that is dimensionally stable during the lamination process may be used for the mould, for example stainless steel. The mould 110 is preferably made of a material that does not adhere to the second sheet of glass 94 and/or the pattern plate 100 and may be made of the same material as the pattern plate. In this example the mould 110 does not adhere to the second major surface 94b of the second sheet of glass 94 or to the second major surface 100b of the pattern plate 100.

It is advantageous if there is a gap between the edge of the pattern plate and the edges of the second sheet of glass 94 and the second sheet of PVB to help with de-airing during lamination.

The entire assembly of first sheet of glass 84, first sheet of PVB 86, sheet of PET 88, second sheet of PVB 92 and second sheet of glass 94 prior to lamination (with or without the pattern plate 100 and/or mould 110) may be referred to as an unlaminated stack.

The unlaminated stack including the spacer and mould in position as described above is then laminated at a temperature in the range 90 °C to 140 °C and a pressure in the range 8 bar to 16 bar. Lamination is possible at a higher temperature, but this is not desirable due to potentially affecting the optical quality in the upper region 83 and/or the increased energy usage required to produce the laminated glazing.

After lamination, if used, mould 110 may be removed from the second sheet of glass 94 and the pattern plate 100.

The pattern plate 100 may be removed from the exposed portion of the second major surface 88b of the sheet of PET 88 because the pattern plate 100 does not adhere thereto.

The pattern in the first major surface 100a of the pattern plate is transferred to the interlayer structure in the lower region 85, that is to the parts of the first sheet of PVB 86 and the sheet of PET 88 in the lower region 85, for example in a similar way to that shown in figures 8 and 9. The lamination temperature may be kept sufficiently low to ensure the pattern imparted or transferred to the lower region 85 has the desired visibility.

Although when installed in a vehicle the pattern in the lower region 85 may not be observable by a driver of the vehicle, the pattern may provide other information that is useful prior to the glazing being installed in the vehicle.

Although in the previous figures the laminated glazings are shown as being flat (or planar) having a flat outer surface, the laminated glazings may be curved in one or more directions. The radius of curvature in one of the one or more directions may be between 1000mm and 8000mm. When the laminated glazing is curved in two directions, suitably each direction of curvature is orthogonal to the other. Suitably the radius of curvature in one or both directions of curvature is between 1000mm and 8000mm.

Suitable techniques are known for shaping the first sheet of glass i.e. gravity sag bending, press bending etc. However the second sheet of glass may be initially flat and “cold formed” to the desired shape set by the curved first sheet of glass by applying suitable pressure to the flat second sheet of glass during the lamination process. The temperature during the lamination process is sufficient to cause to the adhesive layer (i.e. a sheet of PVB) to bond to the first and second sheets of glass, but such temperature is not sufficient to cause the second sheet of glass alone to be deformed by pressing between complementary shaping members and/or sagging under the influence of gravity.

Figure 14 is a flowchart to illustrate the steps used in carrying out a method in accordance with the present invention.

At 250 a sheet of soda-lime-silicate glass having a thickness between 1mm and 25mm is provided. At step 251, the sheet of soda-lime-silicate glass is placed on a suitable support (i.e. a table) with one of the major surfaces faces upwards.

At 252 a first sheet of PVB having a thickness between 0.3mm and 0.8mm is provided. At step 253 the first sheet of PVB is positioned on the sheet of soda-lime-silica glass. The first sheet of PVB may be identically sized in outline to the sheet of soda-lime-silicate glass provided at 250, or may be oversized relative to the outline of the sheet of soda-lime-silicate glass. If the first sheet of PVB provided at 252 is oversized, the first sheet of PVB may be trimmed to size by suitably cutting the first sheet of PVB when positioned on the sheet of soda-lime-silicate glass, using the sheet of soda-lime-silicate glass as a template.

At 254 a sheet of PET having a thickness between 50pm and 200pm is provided. At step 255 the sheet of PET is positioned on the first sheet of PVB. The sheet of PET may be identically sized in outline to the sheet of glass provided in at 50, or may be oversized. If the sheet of PET provided at 54 is oversized relative to the sheet of soda-lime-silicate glass and/or the first sheet of PVB, the sheet of PET may be suitably trimmed to size.

At 256 a decision is made if further sheets of PVB and glass are to be added. If no further PVB/glass sheets are required in the final glazing pane, a pattern plate is provided at 257 and at step 258 the pattern plate having a pattern on or in a surface thereof is positioned at the desired position on the surface of the PET where the pattern on the pattern plate is required in the resulting laminated glazing pane, with the surface of the pattern plate having the pattern in or on being on contact with the PET. The pattern plate may extend over the entire PET surface or over one or more portion thereof.

At 259 the unlaminated stack with the pattern plate on the sheet of PET is laminated at suitably high temperature and pressure such that the PET sheet is adhered to the sheet of soda-lime-silicate glass by the first sheet of PVB. During lamination the pattern plate is pressed against the sheet of PET to form a pattern in or on the first sheet of PVB and/or the sheet of PET.

At 260, the pattern plate is removed from the laminated glazing pane produced at step 259.

At 261 the patterned laminated glazing is used as a pane in a window.

At 256, if additional sheets of PVB and glass are required in the final laminated glazing pane (for example as shown in figures 8 and 11), the method proceeds to step 262 from step 256 (and not to step 257).

At 262 a second sheet of PVB is provided. The second sheet of PVB has a smaller major surface than the first sheet of PVB and the sheet of PET. At step 263 the second sheet of PVB is positioned on the sheet of PET such that a first portion of the PET is covered by the second sheet of PVB and a second portion of the sheet of PET is not covered by the second sheet of PVB.

At 264 a second sheet of glass is provided, which may be a sheet of chemically strengthened glass having a thickness between 0.4mm and 1.0mm. The sheet of chemically strengthened glass has the same outline as the second sheet of PVB. At step 265 the second sheet of glass is positioned on the second sheet of PVB and the periphery is aligned with the periphery of the second sheet of PVB.

If additional sheets of PVB and glass are required in the laminated glazing pane, the steps 262 to 265 may be repeated.

If no additional sheets of PVB and glass are required in the laminated glazing pane, the method proceeds from decision step 256 to step 257. When following this route, the pattern plate will be positioned on at least part of the second portion of the sheet of PET as defined above in relation to step 263. At step 261 the laminate so produced at the end of step 260 is utilised as a glazing pane, either alone or in combination with one or more other panes of glazing material.

Although sheets of PVB are exemplified in relation to figure 14, other sheets of adhesive interlayer may be used, for example EVA. The first sheet of adhesive interlayer material may be different to the second sheet of adhesive interlayer material.

In an alternative embodiment the first sheet of PVB provided at step 252 and the sheet of PET provided at step 254 may be joined together as a composite ply. The composite ply may be identically sized in outline to the sheet of soda-lime-silicate glass provided at 250 or may be oversized relative to the outline of the sheet of soda-lime-silicate glass. If the composite ply is oversized, the composite ply may be trimmed to size by suitably cutting the composite ply when positioned on the sheet of soda-lime-silicate glass, using the sheet of soda-lime-silicate glass as a template.

If a composite ply as described above is provided at step 252, the PVB layer is positioned on the sheet of soda-lime-silica glass with the PET layer facing upwards and there is no need to provide a sheet of PET at step 254.

The method then follows the steps 256 onwards as previously described.

Figure 15 shows a schematic cross-sectional representation of an insulated glazing unit 280, often known as a double glazed unit.

The insulated glazing unit 280 comprises a first glazing pane 284’ spaced apart from a second glazing pane 294 by a perimeter seal 282 to define an airspace 289. The airspace 289 may also be referred to as a cavity, and the cavity may be filled with air, or a mixture of nitrogen and argon. The cavity may be a low-pressure space, and suitable spacers may be included in the cavity to maintain the spacing of the first and second glazing panes 284, 294.

The first glazing pane 284’ has been made in accordance with the present invention and comprises a sheet of glass 284 having a sheet of PET 288 joined thereto by a sheet of PVB 286. The sheet of PVB 286 is coextensive with the sheet of PET 288. The sheet of PVB 286 is positioned inboard of the periphery of the sheet of glass 284 to allow the perimeter seal 282 to be in direct contact with the sheet of glass 284.

The second glazing pane 294 is a sheet of soda-lime silicate glass having a thickness of 6mm. The second glazing pane has a first major surface 294a facing into the airspace and an opposing second major surface 294b. There may be a coating on one or both major surface 294a, 294b, for example a solar control coating. The sheet of PET 288 has a major surface 288b facing into the airspace 289. The sheet of PET may be used as a carrier for an infrared ray reflecting coating, for example on major surface 288b or the opposing major surface (not labelled).

The interlayer structure consisting of the sheet of PVB 286 and the sheet of PET 288 has a pattern formed therein in accordance with the present invention. A suitable pattern plate (not shown) was pressed against the major surface 288b of the sheet of PET 288 during a lamination process to produce the first glazing pane 284’. The pattern in the interlayer structure may be used to provide the insulated glazing unit 280 with an obscuration function, where privacy and high light transmission through the insulated glazing unit are required. Such a pattern may scatter light. In the aforementioned examples the PVB used may be clear or may have one or more additional property, for example the PVB may be tinted, be acoustic modified or be optically scattering i.e. translucent PVB or have a solar control function.

The present invention provides methods for making a glazing pane having a pattern and comprising a first sheet of plastic material laminated to a first sheet of glazing material by means of at least a first sheet of adhesive interlayer material. An interlayer structure comprising the first sheet of an adhesive interlayer material and the first sheet of plastic material is positioned on the first sheet of glazing material. A pattern plate having a pattern on or in a first major surface thereof is positioned on the first sheet of plastic material such that the first major surface thereof faces the first sheet of plastic material. The first sheet of glazing material is then laminated to the first sheet of plastic material via the first sheet of adhesive interlayer material. Thereafter, the pattern plate is removed from the first sheet of plastic material. During lamination, the pattern plate is pressed against the first sheet of plastic to form a pattern in the interlayer structure.

The present invention finds particular application in the field of glazings for buildings and vehicles.